This invention relates to a cooling apparatus for a closed housing cut off from the outside atmosphere, more specifically to a cooling apparatus provided with a heat-pipe-type heat exchanger and adapted to be mounted on a closed housing which contains therein electronic equipment to be protected from the outside atmosphere.
Recently, the application of electronic equipment, especially computers, have been remarkably extended, and process computers have come to enjoy use in even job sites in factories. Ambient air in a job site may contain dust or poisonous gas which has a bad influence upon the process computer and may cause malfunction thereof. In order to be protected from the outside environment, therefore, the process computer needs to be contained in a closed housing.
During operation, however, the process computer generates heat, whereas the closed housing cannot be ventilated without affecting the performance of the process computer. Unless the interior of the housing is cooled, therefore, the process computer cannot help being heated by heat which is internally generated from itself. If heated, the process computer is liable to malfunction. Accordingly, there is proposed a cooling apparatus for a closed housing provided with a heat-pipe-type heat exchanger.
FIG. 1 shows a cooling apparatus 12 for a closed housing 10. The cooling apparatus 12 is provided with a cooling chamber 14 which is attached to one side face of the closed housing 10 in which a process computer is provided. The cooling chamber 14 is divided into two isolated parts, upper and lower chambers 18 and 20, by a partition wall 16 extending horizontally. The upper chamber 18 communicates with the outside air by means of an outer inlet opening 22 and an outer outlet opening 24. The lower chamber 20 communicates with the interior of the closed housing 10 by means of an inner inlet opening 26 and an inner outlet opening 28. Exhaust fans 30 and 32 are disposed inside the outer outlet opening 24 of the upper chamber 18 and the inner outlet opening 28 of the lower chamber 20, respectively. The outside air flows through the upper chamber 18, and air in the housing 10 flows through the lower chamber 20 by means of their corresponding fans 30 and 32. A plurality of heat pipes 34 containing a refrigerant therein airtightly penetrate the partition wall 16 along the vertical direction each with both end portions located in the upper and lower chambers 18 and 20, respectively. Each heat pipe 34 is fitted with a multitude of fins 36 along the axial direction. The upper end portions of the heat pipes 34 are defined as a refrigerant condensing section, while the lower end portions are defined as a refrigerant evaporating section.
In the cooling apparatus thus constructed, the interior of the closed housing 10 is cooled in accordance with the following processes. Air in the closed housing 10 heated by heat generated from the process computer is introduced through the inner inlet opening 26 into the lower chamber 20 by the fan 32. The introduced air is caused to make heat exchange by means of the evaporating section of the heat pipes 32 and the fins 36. As a result, the heat of the air is absorbed by the heat pipes 34 to cool the air, and the refrigerant is evaporated at the evaporating section of the heat pipes 34 to which the heat is applied. The cooled air is returned through the inner outlet opening 28 to the interior of the housing 10 to cool the same.
Meanwhile, the heated and evaporated refrigerant rises up through the heat pipes 34 to reach the condensing section inside the upper chamber 18. The outside air is introduced through the outer inlet opening 22 into the upper chamber 18 by the fan 30, and is caused to make heat exchange by means of the condensing sections of the heat pipes 34 and the fins 36. Accordingly, the heat of the refrigerant is absorbed by the outside air. As a result, the outside air is heated, while the refrigerant is cooled and condensed. The condensed refrigerant falls down to the evaporating section by its own weight, and the heated outside air is discharged through the outer outlet opening 24 into the outside space.
Thus, the air inside the closed housing 10 is caused to exchange heat with the outside air and thence to be cooled by means of the heat pipes 34. Namely, the housing 10 is cooled inside as it is closed, so that the process computer contained in the housing 10 may be protected from dust and heat.
Mounted on one side face of the closed housing 10, however, the prior art cooling apparatus 12 has the following drawbacks. First, the side face of the housing 10 is subject to a restriction on size depending on the setting conditions of the housing 10, as well as to many other restrictions attributed to the attachment of a door, meter, harness, connector, etc., thereon, so that the cooling apparatus 12 need be designed according to the particulars of the individual housing 10. Accordingly, it is difficult to put the cooling apparatus 12 to general use, and the apparatus cannot enjoy any reduction in cost. Secondly, due to the setting location of the cooling apparatus 12 on the side wall of the housing 10, the housing 10 requires an increased setting space when it is arranged in line with another one or put by a wall. Thirdly, whereas the upper portion is at the highest temperature inside the housing 10, the cooling apparatus 12 is attached to one side face of the housing 10 with the evaporating section located in the lower position. Accordingly, the air inlet opening 26 in the housing 10 has to be located in a relatively low position, constituting a hindrance to the improvement of cooling efficiency.